Kazuo Sugimoto starts as an ordinary young salaryman in Japan. A false accusation of molesting a girl on a train drastically alters his life, leading to a forced confession. Determined, Kazuo tracks down the actual perpetrator. Confronting this man results in Kazuo becoming his 500th apprentice in the discipline known as Chikan-do, or The Way of the Groper.

Under this tutelage, Kazuo commences formal training in specialized groping strategies and techniques, studying named tactics including The Berlin Wall and The Battle of Odawara. He works diligently throughout his training to develop and perfect his own unique method, The Gold Finger. His journey involves mastering the philosophy and practical application of Chikan-do.

The apprenticeship transforms Kazuo from an ordinary individual into a practitioner of this specific discipline. His development focuses on acquiring technical proficiency and adapting to Chikan-do's principles. The training reshapes his approach to interactions within crowded public spaces, particularly trains.

Kazuo's background as a salaryman contrasts with his later activities. His character development illustrates a transition from conventional societal participation to engagement with this underground practice. The narrative follows his progression through the apprenticeship stages, highlighting his dedication to mastering the techniques of Chikan-do. His efforts culminate in the creation and refinement of his signature method, The Gold Finger, as part of this training regimen.